Low Temperature Solar Thermal

What are Low Solar Thermal Energy Systems?

Low solar thermal energy systems use radiation from the sun to heat up domestic or commercial water supplies. The incident solar radiation heats up a transfer fluid, which is pumped through a heat exchanger that is connected to the water supply. Examples of such systems include flat plate and vacuum tube roof top collectors. Low thermal energy systems can also apply to passive solar space heating.

What are the challenges for Low Solar Thermal Energy Systems?

In high latitudes, low solar thermal systems do not generate a lot of heat energy in winter, when it is needed most. Increasing the efficiency of the plates so they can absorb more energy in winter is a significant challenge. Losses occur through the transfer of heat from the tubes in the panels to the hot water system. Furthermore, the storage tanks can be quite large and inconvenient to house. The challenge is to build more effective and space efficient solar thermal water systems for use in Northern Eurpean climates.

How are these challenges being addressed by SISER researchers?

Researchers at Edinburgh Napier University are investigating the underlying heat transfer process to improve the efficiency of low solar thermal systems. This is achieved by modelling heat transferring mechanisms in low solar thermal collectors and comparing the results with real systems. Napier University are also looking into ways to reduce space heating within buildings and to exploit the warmth from daylight by using aerogel windows.

Glasgow Caledonian University are developing an anidolic (non-imaging optic) concentrator solar thermal system. The aim of this system is to improve the collector performance by increasing the temperature of water at high latitudes during winter time, while avoiding overheating during the summer. They are also undertaking rsearch into built-in-storage solar water heaters.

Heriot-Watt University are carrying out work on developing storage of solar thermal energy within solid stone walls of tenement buildings. This will maximise heat ollection by using the solid stone mass of the wall as a thermal store. It will also reduce the loss of effiiciency due to the time lag between suply and demand.

Flat plate absorbers provide an elegent solution for harnessing the power of the sun to provide hot water. Simulation and outdoor testing are being carried out on such devices within SISER to optimise their efficiency. Please click on the image to expand.